Study On PLIF/PIV Measurement Method For Local Flow Parameters Of Inclined Liquid-liquid Two-Phase Flow

The liquid-liquid two-phase flow phenomenon are frequently encountered in petroleum,chemical,pharmaceutical,and other vital industrial production fields,and the measurement of local flow parameters is of great significance to reveal the fluid dynamics and optimize the industrial production process.However,due to the obvious differences in physical properties such as viscosity and density of two phases,and the complex interaction of the interface between phases,a variety of flow structures in twophase flow shows significant instability,which brings severe challenges to the measurement of local flow parameters.In this thesis,the local flow parameters such as local phase distribution and velocity distribution of horizontal and inclined liquid-liquid two-phase flow have been accurately measured by the laser visualization method.Firstly,the PLIF-60 test system along the radial section of the pipeline is designed to capture liquid-liquid two-phase flow images.The 3D flow structure of liquid-liquid two-phase flow is visualized by 2D correction and 3D reconstruction,and the morphology of large-scale stratified interface,entrainment characteristics of smallscale droplets and evolution of flow structure are revealed.Then,the axial and radial height sequences of the PLIF image are extracted,and the instability characteristics of the stratified interface are studied by the Energy spectrum and Markov entropy algorithm.Finally,a PIV & PLIF-90 test system,which can measure the velocity field of horizontal and inclined two-phase flow is established along the axial section of the pipeline,and the influence of inclined pipeline on velocity distribution of two-phase flow has been investigated.The innovative research achievements of this thesis are as follows:1.The PLIF-60 fluid visualization system along the radial section of the pipeline is originally designed.The 2D visualization images are corrected through optical path analysis and image processing,and the 3D flow structures are reconstructed.The 3D reconstruction results can indicate the local structure characteristics and effectively reveal the dynamic evolution of the flow structures in two-phase flow.2.Based on the 2D visualization images measured by the PLIF-60 system,the axial and radial height sequences of the interface between phases are extracted,and the instability characteristics of the stratified interface are studied by Energy spectrum and Markov entropy algorithm.According to the 3D flow structures,the physical mechanism of droplet entrainment is explored.3.The PIV & PLIF-90 fluid visualization system is designed to obtain PIV images and accurately detect the velocity field of horizontal and inclined two-phase flow.Meanwhile,the effects of liquid-liquid interaction and inclined pipe on velocity distribution of two-phase flow are investigated.